LONDON — A saliva test for teen-age boys with mild depression could help identify those who will later develop major depression.

That's the finding of a new study, in which researchers measured a stress hormone in teen boys. They found that the teens with high levels, coupled with mild depression symptoms, were up to 14 times more likely to suffer clinical depression later in life than were those with low or normal levels of the stress hormone.

The test was tried on teen-age girls, as well as on boys -- but it was found to be most effective with boys.